Process and compositions for stiffening textiles



United tates atent Fice 3,311,576 PRGCESS AND CGMPOSITIONS FOR STIFFENING TEXTILES Gunter Tauber, Dusseldorf-Reisholz, and Manfred Bohr and Joachim Gaiinhe, Dusseldorf-Holthausen, Germany, assignors to Henkel & Cie, G.m.h.H., Dusseldorf-Holthausen, Germany No Drawing. Filed May 2, 1963, Ser. No. 277,434 Claims priority, application Germany, Apr. 11, 1963, H 48,821 17 Claims. (Cl. 26fl17) This invention relates to a process for stiffening of textiles, which are subjected to repeated laundering, with a stitiening agent which is applied to the fiber and is insoluble in cold or hot water as well as in neutral-reacting washing agent solutions, that is, under the conditions of so-called fine laundering, but still soluble in alkaline-reacting washing solutions even after ironing. The stiffening agent consists of dispersions of water-insoluble copolymers of the polyvinyl ester containing free carboxyl groups, said dispersions having been prepared in the presence of protective colloids and possibly emulsifiers.

It is known that aqueous dispersions of polyvinyl acetate may be used for finishing and stiffening of textiles. As against the conventional starch finishes, these stiffening compositions have the property that they are not, or only to a minor extent, removed from the fiber during laundering and that, therefore, a distinct stiffening eifect is still present after several launderings. Consequently, wash-resistant finishes based on polyvinyl acetate are often used as initial or permanent finishes.

Such polyvinyl acetate dispersions are not only used as initial finishes, but also as stiffening agents for household textiles which are subjected to repeated launderings. Since the synthetic resin impregnation is not, or only to a very minor extent, removed from the fiber during laundering, the textile material once treated does not require a subsequent treatment with highly dilute dispersions until after a certain number of launderings in order to maintain the desired degree of stiflness. However, the advantage of the high wash-resistance of such permanent stiifeners is, on the other hand, connected with substantial disadvantages. It has been found that soil adheres more firmly to textiles finished with the permanent stifleners than to textiles treated with starch compositions. The stubbornly adhering soil residues can no longer be completely removed from the fiber, even even by repeated laundering. If the impregnation treatment is repeated from time to time in order to maintain a certain degree of stiffness, these soil residues are insolubly fixed on the film by the newly applied layer of synthetic resin. Therefore, after only a short period of use the textile material shows a substantial grey dinginess which can no longer be removed by presently known washing or bleaching methods.

Moreover, in the case of textiles which are washed very often, such as underwear, shirts, blouses, and the like, it is practically impossible to judge, while the items are wet, to what extent a new treatment with stiliening agent is necessary after laundering, which makes it very difiicult to select the correct dosage for the treatment with permanent stifiener. The excess stifiness and hardness of the textile material, which occurs after repeated application or excess dosages, can no longer be reversed. The film of synthetic resin, which adheres as a relatively thick layer to the film, has a strong tendency toward yellowing due to the influence of light as well as because of the efiects of increased temperature during washing and ironing. Improperly treated textile items therefore become unsightly after a relatively short time.

It has further been suggested to use an aqueous alkaline solution of copolymers of vinyl acetate and unsaturated polymerizable acids, such as acrylic acid, methacrylic acid, crotonic acid, maleic acid or fumaric acid, as in initial finish for textiles, for 'instane as a halt stiffener. These copolymers are used not only in aqueous alkaline solution in the form of their alkali metal salts, but also in the form of their free acids, namely dissolved in organic solvents, especially in lower alkanols. In order to achieve an adequate degree of coating, however, relatively highly concentrated solutions with a solids content above 5% by weight must be used, and the treatment of the textile material must in most cases be repeated several times. Because of their high viscosity and tackiness, such concentrated solutions are very difiicult to apply. The finishing process, therefore, often requires machinery and, when organic flammable solvents are used, extensive safety devices, whereby their use in the household is excluded. The preparation of such vinyl acetate copolymers is often accomplished in an aqueous by suspensionor bead-polymerization, whereby the resins are obtained in the form of small, rapidly precipitating spheres which are dissolved, as described above, in alkalies or alcohols and are app-lied in that form. The use of such coarsely dispersed and unstable resin suspensions is not claimed in the present case.

If the polymerization is performed in aqueous phase, using suflicient amounts of protective colloids or emulsifiers or mixtures of these macroscopic, homogeneous, spreadable and free-flowing emulsions with a particle diameter below 7 most-ly below 4 are formed. It has become customary to designate emulsions with coarse particles, which have a particle diameter above 0.1 preferably 0.5 to 3 as dispersions. The dispersions used in accordance the present invention also have a particle diameter between 7 and 0.1 preferably 0.5 to 4 Customary protective colloids for highly concentrated, highly viscous dispersions based on copolymers of vinyl acetate with copolymerizable carboxylic acids are particularly polyvinyl alcohol and partially saponified polyvinyl acetate. However, relatively large amounts of such protective colloids are required for a sufiicient stabilization of the dispersions. For instance, copolymer dispersions with improved storage stability are obtained by adding only a part of the polyvinyl alcohol or partially saponified polyvinyl acetate to the monomer mixture at the beginning of the polymerization, and adding the major amount of protective colloid to the finished dispersion subsequent to the polymerization. Such particularly cold-stable, viscous dispersions, to which the high polyvinyl alcohol content imparts a high tackiness and which are therefore of particular interest in the field of adhesives, have been suggested for use also as textile finishing agents, such as sizing agents. However, the synthetic resin films produced from these dispersions are relatively soft, and because of this property the soiling tendency of the textile material treated therewith is increased. The large amounts of polyvinyl alcohol reduces the water-stability of the finish, so that it swells considerably in water or fine washing solutions and is partially removed from the fiber. On the other hand, at the customary ironing temperatures, which lie above 100 C., a partial cross-linking of the synthetic resin film on the fiber takes place. This cross-linking has the effect that the synthetic resin film substantially loses its alkali solubility and can no longer be removed from the fiber to a sufiicient degree. For this reason such copolymer dispersions have no advantages over the known permanent stifieners based on homopolymeric polyvinyl acetate. Nothing is known about the type of cross-linking. It is well known that polyvinyl alcohol can be cross-linked thermally, but in general much higher temperatures are required therefor. It is possible that the free carboxyl groups of the copolymer facilitate the cross-linking or enter into the reaction themselves.

It is, therefore, an object of this invention to provide a method for providing a stiffening finish for textiles which is relatively permanent under neutral conditions but removable under alkaline conditions.

A further object is to provide a method for stiffening textiles wherein the finishing agent is not adversely affected by heat of ironing or soil.

These and other objects of the invention will be apparent as the description thereof proceeds.

The invention attains the above objects and overcomes the above recited difficulties. It has surprisingly been found that alkali-soluble dispersions which do not contain polyvinyl alcohol but instead other water-soluble high polymers, such as copolymers'of acrylamide or cellulose products, as a protective colloid produce fibers which do not cross-link upon being heated to temperatures which occur during normal ironing, but instead completely retain their alkali-solubility. This is also surprising inasmuch as hydroxyethyl cellulose, for instance, also contains hydroxyl groups. The subject matter of the present invention is a process for stiffening of textiles, which are subjected to repeated landering, with a stiffening agent which is applied to the fiber and is insoluble in cold or hot water as Well as in neutral-reacting washing agent solutions, that is, under the conditions of so-called fine laundering, but still soluble in alkaline-reacting washing solutions even after ironing. The stiffening agent consists of dispersions of water-insoluble copolymers of the polyvinyl ester containing free carboxyl groups, said dispersions having been prepared in the presence of protective colloids and possibly emulsifiers.

The preparation of the dispersion, which is not here claimed, is effected, for example, according to copending application Ser. No. 277,436, that is, by polymerizing vinyl esters together with an unsaturated polymerizable monocarboxylic acid, such as acrylic acid, methacrylic acid, crotonic acid, or a similar dicarboxylic acid, such as maleic acid, fumaric acid or itaconic acid, as well as their semi-esters, in the presence of a protective colloid and possibly an emulsifier as well as in the presence of a water-soluble peroxide-catalyst. The content of unsaturated carboxylic acids in the copolymer should advantageously not be less than 2 and no more than 10 mol percent, preferably 3 to 7 mol percent, since the polymers with a lesser acid content have an insufficient alkali solubility, and those with a higher acid content have an un desirable swelling property in water;

Suitable vinyl esters are those whose acyl radicals contain 2 to 4 carbon atoms, that is, vinyl acetate, vinyl propionate, vinyl butyrate, as well as mixtures thereof. It is preferred to use copolymers of vinyl acetate.

The dilspersions contain as protective colloids high molecular substances which are soluble in water, such as polyacrylamide, copolymers of acrylic acid amide or methacrylic acid amide with acrylic acid esters, copolymers of acrylic acid amide with N-substituted acrylic acid amides or water-soluble cellulose derivatives, such as hydroxyethyl cellulose. The protective colloids are employed in an amount of 0.5 to 7%, preferably 1.0 to 5%, based on the molecular content.

Particularly advantageous properties are possessed by those dispersions which contain as protective colloids water-soluble copolymers of acrylamide and lower N- alkylacrylamides with a chain length of 2 to 6 carbon atoms. Such dispersions are characterized by an unusually high storage stability at a protective colloid content of only 0.5 to 3%, based on the vinyl acetate copolymer.

In the event that the water-soluble protective colloids possess certain surfactive properties, such as the copolymers of acrylamide and N-tert.-butylacrylamide, it is possible to forego the concurrent use of emulsifiers, or only very small quantities thereof are required. In

general, less than 1% of emulsifier, based on the monomer, is sufficient. Suitable emulsifiers are ionic and nonionic emulsifiers, such as fatty alcohol sulfates, fatty alcohol glycol ethers and sulfonic acid esters and phosphoric acid esters thereof. It is further possible to add to the above described synthetic resin dispersions certain additional substances, such as ironing assistants, wetting agents, optical brighteners, and the like, prior to their application as stiffening agents in order to achieve certain additional effects in use.

For use in accordance with the present invention the dispersions are diluted with water to a solids content of 0.055% by weight, preferably 0.15 to 1% by weight. Higher concentrations produce only a small increase and are not in general required for household laundering.

For the preparation of a polyvinyl ester dispersion which is suitable for use as a laundry stiffener and is characterized by special advantages, such as long shelf life of the dispersion, high achievable stiffening degrees and. pleasant feel of the treated textiles, high resistance against water and neutral-reacting fine washing solutions and good solubility in alkaline reacting washing solutions, the starting composition may for example be composed as follows:

40-60% of a monomeric mixture of vinyl ester and a content of 3 to 7 mol percent of coploymerizable carboxylic acids O.53% of a copolymer of acrylamide and N-butylacrylarnide (molar ratio 1:3 to 3:1)

0-l% of an ionic and/or non-ionic emulsifier or emulsifier mixture (ll-0.5% of a water-soluble polymerization catalyst mixture Remainder: water The dispersion is diluted for use with Water to a solids content of 0.12%.

The above-described stiffening compositions may be employed in the same manner as the commercial permanent stiffeners based on synthetic resins. For example, the textile material to be treated is immersed into the dilute dispersion and is all-owed to remain therein for some time. In order to achieve a uniform impregnation it is recommended that the textile material be agitated during the treatment. The application of the stiffening composition to the fabric may easily be followed by means of the retrogression of the turbidity in the solution. The degree of turbidity at the same time gives a clue as to what extent the bath is already exhausted and whether a fresh stiffening agent must possibly be added thereto. Of course, the correspondingly diluted dispersions may also be sprayed onto the textile material. Subsequent to the treatment, the textile pieces are freed from excess moisture by wringing or centifuging, and are then ironed as usual.

The textiles treated in accordance with the present invention exhibit varying degrees of stiffness, depending on the concentration of the dispersion. Even at high concentrations the stiffened fabrics remain elastic and retain a pleasant feel without being tacky. The stiffening effect is equally resistant against repeated treatment with cold and hot water as well as neutral fine Washing solutions as well as against mechanical stress. In the event that it is desired. the synthetic resin stiffness may, however, also be completely removed by a normal alkaline washing treatment, possibly by boiling under alkaline conditions. In this manner the disadvantageous consequences of an excessively frequent application or excess dosage of the stiffening agent, but especially the above described graying and yellowing effects of the treated fabrics, can be substantially avoided. Thus, a laundry stiffener which is simple to use is made available particularly to the private consumer, and he may leave it on the fiber or also completely remove it during cleaning of the textiles, depending on the requirements.

The following specific examples are presented to illustrate the invention and to enable persons skilled in the art to better understand and practice the invention and are not intended to be limitative.

The percentage figures given in the following examples represent percent by weight.

Example I For the preparation of the synthetic resin dispersion pursuant to copending application Ser. No. 277,436 the procedure was as follows: 6 gm. of a protective colloid (copolymer of 50% acrylamide and 50% tert.-butylacrylamide) were dissolved in 225 cc. of water, and 1.4 gm. of sodium lauryl sulfate as well as 18 gm. of a emulsifier solution were added thereto. The emulsifier was produced by addition of 8 mols ethylene oxide to coconut fatty alcohol and subsequent reaction with phosphorous pentoxide in a molar ratio of 2:1. 10% of a mixture of 279 gm. of vinyl acetate and 9.6 gm. of crotonic acid were added to the solution heated to C. while introducing nitrogen and stirring the solution. After adding an aqueous solution of 1.36 gm. of potassium persulfate and 0.06 gm. of sodium sulfite, the mixture was heated to C. As soon as the polymerization egan, 0.48 gm. of sodium bicarbonate dissolved in water was added thereto, and the mixture of vinyl acetate and crotonic acid was added dropwise over a period of two hours accompanied by stirring. Thereafter, an aqueous solution of 0.34 gm. of potassium persulfate was added and the polymerization was brought to completion by heating to 90 C. After cooling, a homogeneous, stable dispersion was obtained which had an Epprecht viscosity of 1000 to 1500 cp. (25 C.) and a solids content of about 50%. The acid number of the dispersion was 16, that is, 1 gm. of the dispersion consumed 16 mgm. of potassium hydroxide, titrated against phenolphthalein.

The dispersion thus obtained was divided into three parts, each of which was diluted with water to a solids content of 0.15%, 0.3% and 0.5%, respectively. Previously washed pieces of linen and cotton fabric were introduced into these dispersions and were agitated from time to time. The solution ratio was gm. of fabric per 1 liter of solution. After ten minutes the textile samples were withdrawn from the solution, wrung out, and after a short period of drying, were ironed in a slightly moist state. Of these textile samples those treated in the 0.15% solution exhibited a distinct degree of stiffening, those treated in the 0.3% solution a medium degree of stiffening, and those treated in the 0.5% solution a high degree of stiffening.

Two pieces of each of the stiffened samples were boiled for ten minutes in an alkaline washing solution containing organic surfactants, soda, sodium silicate and phosphates. An identical number of samples were washed in a neutral fine washing solution at 40 C. for

15 minutes, and another series of samples was treated for 10 minutes with hot water at 80 C. After drying and ironing, the samples washed with fine soap solution and with the hot water exhibited the same degree of stiffness as the samples which had not been washed. In contrast thereto, the stiffness was completely washed out of the fabrics subjected to boiling under alkaline conditions.

Example II A dispersion with a solids content of 50%, a viscosity of 16,000 cp. (25 C.) and an acid number of 15.5 was prepared by a method analogous to that described in Example I, using the following materials:

Starting from 300 gm. of water,

6 gm. of the protective colloid used in Example I, 18 gm. of the emusifier used in Example I,

2.8 gm. of sodium lauryl sulfate,

1.8 gm. of potassium persulfate,

0.48 gm. of sodium bicarbonate,

6 0.06 gm. of sodium sulfite, 18 gm. of maleic acid butyl semiester, and 270 gm. of vinyl acetate.

In the dispersion diluted to a solids content of 0.3%, textile items of cotton were starched as described in Example 1. After ironing these samples exhibited a medium degree of stiffness and a pleasant feel. A portion of the samples were washed in a fine washing solution heated to 40 C., and another portion at 90 C. with an alkaline soap solution containing soda and alkali metal phosphate in a rotating drum washer. After rinsing, drying and ironing the samples treated with the time washing agent exhibited an undiminished degree of stiffening, whereas the samples treated with the alkaline solution no longer contained any stiffening agent.

Example 111 In a manner analogous to that described in Example I, a low viscosity dispersion was prepared from:

300 gm. water,

6 gm. oxethyl cellulose (Natrasol 250G), 18 gm. of the emulsifier used in Example I, 1.4 gm. of sodium lauryl sulfate,

2.1 gm. of potassium persulfate,

0.06 gm. of sodium sulfite,

9 gm. of crotonic acid, and

279 gm. of vinyl acetate.

The dispersion formed a clear solution in dilute alkalies. Textiles were also stiffened with this dispersion in the manner described in Examples I and II; the synthetic resin stiffener was resistant against neutral washing agents, but it could be removed again from the textile material with the aid of alkaline washing solutions.

Example IV For purposes of comparison with the stiffening agents according to the present invention, a commercial 50% high polymeric polyvinyl acetate dispersion having a viscosity of 8,000 cp. (25 C.) was diluted with water to a solids content of 0.3%. Linen and cotton fabrics were treated with this dispersion in the same manner as indicated in Examples I and II. The samples exhibited the same degree of stiffening as those treated in accordance with the present invention, but the stiffness could not be removed either by fine washing or by prolonged boiling under alkaline conditions.

Example V In a further comparative test, a copolymer dispersion containing polyvinyl alcohol was used. The dispersion was prepared under the exclusion of air by adding dropwise a mixture of 341 gm. of vinyl acetate and 10.5 gm. of crotonic acid to a solution of 11 gm. of polyvinyl alcohol (saponification number in 225 gm. of water at 70 C. The polymerization was initiated by the addition of 1. 8 gm. of potassium persul-fate dissolved in a small amount of water and was carried to completion after four hours of stirring and heating as described in Example I. And about 60% dispersion with a viscosity (according to Epprecht) of about 1500 cp. (25 C.) was obtained, which was found to be less storagestable and especially not cold stable in comparison to the dispersions described in Examples I and H.

A portion of this dispersion was diluted to a solids content of about 50% with a solution of 45 gm. of the above mentioned polyvinyl alcohol in gm. of Water subsequent to the polymerization. The dispersion, whose viscosity (according to Epprecht) was now 6500 cp. (25 C.), was found to be adequately storage-stable and cold-stable.

Ttextile samples were treated in the above described manner with the dispersions diluted to a solids content of 0.5 and certain degree of stiffness was also achieved therewith. The stiffening composition stabilized with additional polyvinyl alcohol, however, was found to be less water-resistant and could be removed by repeated neutral fine washing. However, when the textile samples were ironed, the resin in both cases could no longer be removed from the fiber to a major extent by an alkaline was-hiig process. The polymer adhering to the washed textile samples, however, had substantially lost its stiffening effect.

Example VI In a third series of tests the dispersions prepared according to Examples I and III as well as the dispersions of Example V prepared with polyvinyl alcohol were applied to cleaned glass plates. The synthetic resin films, which had been dried at room temperature, formed a clear solution within two to three hours in a 1% sodium hydroxide solution at 20 C. Another series of samples was heated for ten minutes in a drying chamber to 100 110 C. and the solubility was again investigated in a 1% sodium hydroxide solution at room temperature as well as at the boiling point in a 1% aqueous crystalline soda solution. The following results were obtained:

The films of the dispersions according to Examples I and III also formed a clear solution within the same period of time in a 1% sodium hydroxide solution at 20 C. after the heat treatment. While the polyvinyl alcohol-containing films of Example V swelled, they remained films even after two days of standing. Upon boiling in a 1% soda solution the films made from the dispersions according to Examples I and III completely dissolved within 10 to 15 minutes, whereas the resin containing the polyvinyl alcohol remained undissolved after 30 minutes.

While certain specific examples and preferred modes of practice of the invention have been set forth it will be understood that this is solely for the purpose of illustration and that various changes and modifications may be made without departing from the spirit of the disclosure and the scope of the appended claims.

In the following claims the term vinyl alcohol group may be understood as the group We claim:

1. Process for providing a stiffening finish to textiles wherein the finish is stable against neutral washing agent solutions but soluble in alkaline washing agent solutions, which comprises treating said textile with aqueous dispersions of copolymers containing free carboxyl groups prepared from vinyl esters of alkanoic acids of 2 to 4 carbon atoms and copolymerizable carboxylic acids having from one to two carboxyl groups in the molecule, said dispersions having been prepared in the presence of protective colloids selected from the group Consisting of water-soluble copolymers of acrylamide with N-alkyl acrylamides having from 2 to 6 carbon atoms in the alkyl radical and water-soluble hydroxyethyl cellulose in an amount from about 0.5 to 7% by weight, which is sub stantially free of reactive vinyl alcohol groups.

2. The process of claim 1 wherein the treating dispersion contains in addition emulsifiers.

3. Process for providing a stiffening finish to textiles wherein the finish is stable against neutral washing agent solutions but soluble in alkaline washing agent solutions, which comprises treating said textiles with aqueous dispersions of copolymers containing free carboxyl groups prepared from vinyl esters of alkanoic acids of 2 to 4 carbon atoms and copolymerizable carboxylic acids hav ing from one to two carboxyl groups in the molecule, said dispersions having been prepared in the presence of protective colloids selected from the group consisting of water-soluble copolymers of acrylamide with N-allcyl acrylamides having from 2 to 6 carbon atoms in the alkyl radical and water-soluble hydroxyethyl cellulose in an 0 amount from about 1 to 5% by weight, which is substantially free of reactive vinyl alcohol groups.

4. Process for providing a stifiiening finish to textiles wherein the finish is stable against neutral washing agent solutions but soluble in alkaline washing agent solutions, which comprises treating said textiles with aqueous dispersions of copolymers containing free carboxyl. groups prepared from vinyl esters of alkanoic caids of 2 to 4 carbon atoms and 2 to 10 mol percent copolymerizable semiesters of unsaturated carboxylic acids having from one to two carboxyl groups in the molecule, said dispersions having been prepared in the presence of protective colloids selected from the group consisting of water-soluble copolymers of acrylamide with N-alkyl acrylamides having from 2 to 6 carbon atoms in the alkyl radical and water-soluble hydroxyethyl cellulose in an amount from about 0.5 to 7% by weight, which is substantially free of reactive vinyl alcohol groups.

5. Process for providing a stiffening finish to textiles wherein the finish is stable against neutral washing agent solutions but soluble in alkaline washing agent solutions, which comprises treating said textiles with aqueous dispersions of copolymers containing free carboxyl groups prepared from vinyl esters of alkanoic acids of 2 to 4 carbon atoms and 3 to 7 mol percent copolymerizable semiesters of unsaturated carboxylic acids having from one to two carboxyl groups in the molecule, said dispersions having been prepared in the presence of protective colloids selected from the group consisting of water-soluble copolymers of acrylamide with N-alkyl acrylamides having from 2 to 6 carbon atoms in the alkyl radical and water-soluble hydroxyethyl cellulose in an amount from about 0.5 to 7% by weight, which is substantially free of reactive vinyl alcohol groups.

6. Process for providing a stiffening finish to textiles wherein the finish is stable against neutral washing agent solutions but soluble in alkaline washing agent solutions, which comprises treating said textiles with aqueous dispersions of copolymers containing free carboxyl groups prepared from vinyl esters of alkanoic acids of 2 to 4 carbon atoms and copolymerizable carboxylic acids having from one to two carboxyl groups in the molecule, said dispersions having been prepared in the presence of protective colloids which are water-soluble copolymers of acrylamide with N-alkyl acrylamides having from 2 to 6 carbon atoms in the alkyl radical, in an amount from about 1 to 5 percent by weight, which is substantially free of reactive vinyl alcohol groups.

7. The process of claim 1 wherein the dispersion is diluted prior to use to a solids content of from about 0.05 to 5 percent by weight.

8. The process of claim 1 wherein the dispersion is diluted prior to use to a solids content of from about 0.15 to 1 percent by weight. 7

9. A stiffening agent for textiles, wherein the finish is stable against neutral washing agent solutions but soluble in alkaline washing agent solutions, which comprises an aqueous dispersion of copolymers containing free carboxyl groups prepared from vinyl esters of alkanoic acids of 2 to 4 carbon atoms and copolymerizable carboxylic acids having from one to two carboxyl groups in the molecule, said dispersions having been prepared in the presence of protective colloids selected from the group consisting of water-soluble copolymers of acrylamide with N-alkyl acrylamides having from 2 to '6 carbon atoms in the alkyl radical and water-soluble hydroxyethyl cellulose in an amount from 0.5 to 7% by weight, which is substantially free of reactive vinyl alcohol groups.

10. The stiffening agent of claim 9 containing in addition emulsifiers.

11. A stiffening agent for textiles, wherein the finish is stable against neutral washing agent solutions but soluble in alkaline washing agent solutions, which comprises an aqueous dispersion of copolymers containing free carboxyl groups prepared from vinyl esters of alkanoic acids of 2 to 4 carbon atoms and copolymerizable carboxylic acids having from one to two carboxyl groups in the molecule, said dispersions having been prepared in the presence of protective colloids selected from the group consisting of Water-soluble copolymers of acrylamide with N-alkyl acrylamides having from 2 to 6 carbon atoms in the alkyl radical and water-soluble hydroxyethyl cellulose in an amount from about 1 to 5% by weight, which is substantially free of reactive vinyl alcohol groups.

12. A stiffening agent for textiles, wherein the finish is stable against neutral washing agent solutions but soluble in alkaline washing agent solutions, which comprises an aqueous dispersion of copolymers containing free carboxyl groups prepared from vinyl esters of alkanoic acids of 2 to 4 carbon atoms and 2 to mol percent copolymerizable semiesters of unsaturated carboxylic acids having from one to two carboXyl groups in the molecule, said dispersions having been prepared in the presence of protective colloids selected from the group consisting of water-soluble copolymers of acrylamide with N-alkyl acrylarnides having from 2 to 6 carbon atoms in the alkyl radical and water-soluble hydroxyethyl cellulose in an amount from about 0.5 to 7% by weight, which is substantially free of reactive vinyl alcohol groups.

13. A stiffening agent for textiles, wherein the finish is stable against neutral washing agent solutions but soluble in alkaline washing agent solutions, which comprises an aqueous dispersion of copolymers containing free carboxyl groups prepared from vinyl esters of alkanoic acids of 2 to 4 carbon atoms and 3 to 7 mol percent copolymen'zable semiesters of unsaturated carboxylic acids having from one to two carboxyl groups in the molecule, said dispersions having been prepared in the presence of protective colloids selected from the group consisting of water-soluble copolymers of acrylamide with N-alkyl acrylamides having from 2 to 6 carbon atoms in the'alkyl radcal and water-soluble hydroxyethyl cellulose in an amount from about 0.5 to 7% by weight, which is substaantially free of reactive vinyl alcohol groups.

14. A stiffening agent for textiles, wherein the finish is stable against neutral washing agent solutions but soluble in alkaline washing agent solutions, which comprises an aqueous dispersion of copolymers containing free carboxyl groups prepared from vinyl esters of alkanoic acids of 2 to 4 carbon atoms and copolymerizable carboxylic acids having from one to two carboxyl groups in the molecule, said dispersions having been prepared in the presence of protective colloids which are watersoluble copolymers of acrylamide with N-alkyl acrylamides having from 2 to 6 carbon atoms in the alkyl radical, in an amount from about 1 to 5 percent by weight, which is substantially free of reactive vinyl alcohol groups.

15. The stiffening agent of claim 9 diluted with water to a solids content of about 0.05 to 5 percent.

16. The stiffening agent of claim 9 diluted with water to a solids content of about 0.15 to 1 percent.

17. A stifiening agent for textiles, wherein the finish is stable against neutral washing agent solutions but soluble in alkaline washing agent solutions, which comprises an aqueous dispersion having a content of (a) from about 40 to percent of copolymers containing free carboxyl groups prepared from vinyl acetate and 2 to 10 mol percent copolymerizable carboxylic acids having from one to two carboxyl groups in the molecule, (b) from about 1 to 5 percent of a water-soluble copolymer of acrylamide and N-butylacrylamide in a ratio of 1:3 to 3:1, and (c) from 0 to 1 percent of emulsifiers.

References Cited by the Examiner UNITED STATES PATENTS 2,504,074 4/1950 Jones 260-29.6 2,533,166 12/1950 Jones 26089.7 2,806,020 9/1957 Scott et al. 26029.6

FOREIGN PATENTS 813,463 5/1959 Great Britain.

MURRAY TILLMAN, Primary Examiner. W. J. BRIGGS, SR., Assistant Examiner. 

1. PROCESS FOR PROVIDING A STIFFENING FINISH TO TEXTILES WHEREIN THE FINISH IS STABLE AGAINST NEUTRAL WASHING AGENT SOLUTIONS BUT SOLUBLE IN ALKALINE WASHING AGENT SOLUTIONS, WHICH COMPRISES TREATING SAID TEXTILE WITH AQUEOUS DISPERSIONS OF COPOLYMERS CONTAINING FREE CARBOXYL GROUPS PREPARED FROM VINYL ESTERS OF ALKANOIC ACIDS OF 2 TO 4 CARBON ATOMS AND COPOLYMERIZABLE CARBOXYLIC ACIDS HAVING FROM ONE TO TWO CARBOXYL GROUPS IN THE MOLEUCLE, SAID DISPERSION HAVING BEEN PREPARED IN THE PRESENCE OF PROTECTIVE COLLOIDS SELECTED FROM THE GROUP CONSISTING OF WATER-SOLUBLE COPOLYMERS OF ACRYLAMIDE WITH N-ALKYL ACRYLAMIDES HAVING FROM 2 TO 6 CARBONATOMS IN THE ALKLY RADICAL AND WATER-SOLUBLE HYDROXYETHYL CELLULOSE IN AN AMOUNT FROM ABOUT 0.5 TO 7, BY WEIGHT, WHICH IS SUBSTANTIALLY FREE OF REACTIVE VINYL ALCOHOL GROUPS. 